DISCLAIMER about pre-patched files

Since Localizer version 1.9, there is no longer a need for the user to patch Drupal core files, or replace any existing Drupal files.

However, the Localizer module itself actually contains pre-patched Drupal core files that Localizer references. These "pre-patched Drupal files" reside safely within the localizer folder, so that in the event you disable Localizer or uninstall it (meaning deleting the localizer directory), the patches are also disabled or uninstalled at the same time.

As one might guess, these pre-patched files are associated with a specific version of Drupal. Therefore, the version of Localizer that you use must specifically be for a certain (minor) version of Drupal. Also, if for some reason you have hacked the Drupal core equivalents of the same files, you will probably want to apply the patches yourself rather than using the pre-patched files. (If you are good enough to have hacked them in the first place, you can figure out how to do this right?!)

If you update Drupal core without updating Localizer to the corresponding version as well, your site may cease to work. It all depends on what was changed in Drupal core for the minor update.

Even if it does work, if you use the Update status module, your Drupal version shown under Administer > Logs > Available updates will be incorrect because the "older" pre-patched core files under the localizer directory will be referenced.

Anyway, what this all means is that it is probably best to update your Localizer-enabled Drupal 5.x site after the author has made the corresponding version available so that you can upgrade both at the same time. However, please realize that there will always be some lag time between a Drupal 5.x minor revision and the Localizer module also getting the "fixes" for the minor revision, and sometimes that lag time may be significant due to the author's workload, etc.